aoa_t4 module

Angle of Attack (AOA) sensor using angle input from a modiefied hall servo connected to a T4 Actuators Board.

For the hardware and software used to make your own T4 Actuators board, find all information here:

https://github.com/tudelft/t4_actuators_board/

To make it work, the motor of the servo needs to be removed, only the hall sensors is used for angle feedback. If the MOTOR is NOT REMOVED from the servo there will be to much friction and the sensor will NOT WORK properly.

Budget wise it is a flexible solution for angle of attack sensor if one uses a T4 Actuators Board already.

Aditionall a second servo can added to be assigned to fuction as a SideSlip angle (SSA) sensor.

If SSA is added, it is assumed that both sensors are the same, offset and direction can be set to different values.

A Servo modified for sensor use which works well is a Feetech STS3032. It is a 360 degree serial bus servo with hall sensor feedback.

Simply add the "aoa_t4" module to your myname_airframe.xml file to be able to use this solution. Also for initial offset determination, enabeling the SYNC message is very helpfull. Just add the SYNC_SEND_AOA_T4 define.

For a 3D design of a vane that can be 3D printed and mounted on the servo used, download it here:

Example for airframe file

Add to your firmware section: This example contains all possible configuration options, not all of them are mandatory!

<module name="aoa_t4">
  b'<define name="AOA_T4_SERVO_ID" value="10" />\n    '
  b'<define name="AOA_T4_ANGLE_OFFSET" value="3.14" />\n    '
  b'<define name="AOA_T4_OFFSET" value="-0.123" />\n    '
  b'<define name="AOA_T4_REVERSE" value="TRUE|FALSE" />\n    '
  b'<define name="AOA_T4_USE_FILTER" value="TRUE|FALSE" />\n    '
  b'<define name="AOA_T4_FILTER" value="0.08" />\n    '
  b'<define name="AOA_T4_SYNC_SEND" value="TRUE|FALSE" />\n    '
  b'<define name="AOA_T4_USE_COMPENSATION" value="TRUE|FALSE" />\n    '
  b'<define name="USE_AOA" value="TRUE|FALSE" />\n    '
  b'<define name="AOA_T4_COMP_A1" value="0.0" />\n    '
  b'<define name="AOA_T4_COMP_B1" value="0.0" />\n    '
  b'<define name="AOA_T4_COMP_A2" value="-0.34" />\n    '
  b'<define name="AOA_T4_COMP_B2" value="0.0" />\n    \n    '
  b'<define name="SSA_T4_SERVO_ID" value="9" />\n    '
  b'<define name="SSA_T4_ANGLE_OFFSET" value="3.14" />\n    '
  b'<define name="SSA_T4_OFFSET" value="-0.456" />\n    '
  b'<define name="SSA_T4_REVERSE" value="TRUE|FALSE" />\n    '
  b'<define name="SSA_T4_USE_FILTER" value="TRUE|FALSE" />\n    '
  b'<define name="SSA_T4_FILTER" value="0.15" />\n    '
  b'<define name="USE_SIDESLIP" value="TRUE|FALSE" />\n  '
</module>

Module configuration options

Define Options

• name: AOA_T4_SERVO_ID value: 10
  Description: Set the Servo ID of servo to use as an Angle Of Attack(AOA) sensor.
• name: AOA_T4_ANGLE_OFFSET value: 3.14
  Description: How the sensor is physically mounted, a global offset in radian corresponding to the sensor mounting (default: 3.14)
• name: AOA_T4_OFFSET value: -0.123
  Description: Initial offset on the neutral angle value.
• name: AOA_T4_REVERSE value: TRUE|FALSE
  Description: Set to TRUE to reverse AOA output rotation direction (sign)
• name: AOA_T4_USE_FILTER value: TRUE|FALSE
  Description: Filter the AOA angle sensor output to avoid to much angle fluctuation
• name: AOA_T4_FILTER value: 0.08
  Description: If filtered is true, then set how much to filter the output
• name: AOA_T4_SYNC_SEND value: TRUE|FALSE
  Description: Enable telemetry report from AOA or SSA sensor, best set to TRUE to determine the neutral angle to set in offset
• name: AOA_T4_USE_COMPENSATION value: TRUE|FALSE
  Description: Compensate the output
• name: USE_AOA value: TRUE|FALSE
  Description: Enable AOA sensor values to the state (default: TRUE)
• name: AOA_T4_COMP_A1 value: 0.0
• name: AOA_T4_COMP_B1 value: 0.0
• name: AOA_T4_COMP_A2 value: -0.34
• name: AOA_T4_COMP_B2 value: 0.0
• name: SSA_T4_SERVO_ID value: 9
  Description: Set the Servo ID of servo to use as an SideSlip Angle(SSA) sensor
• name: SSA_T4_ANGLE_OFFSET value: 3.14
  Description: How the sensor is physically mounted, a global offset in radian corresponding to the sensor mounting (default: 3.14)
• name: SSA_T4_OFFSET value: -0.456
  Description: Initial offset on the neutral angle value.
• name: SSA_T4_REVERSE value: TRUE|FALSE
  Description: Set to TRUE to reverse AOA output rotation direction (sign)
• name: SSA_T4_USE_FILTER value: TRUE|FALSE
  Description: Filter the AOA angle sensor output to avoid to much angle fluctuation
• name: SSA_T4_FILTER value: 0.15
  Description: If filtered is true, then set how much to filter the output
• name: USE_SIDESLIP value: TRUE|FALSE
  Description: Enable SSA sensor values into the state

Module functions

Init Functions

These initialization functions are called once on startup.

• aoa_t4_init()

Periodic Functions

These functions are called periodically at the specified frequency from the module periodic loop.

• aoa_t4_update()
  • Frequency in Hz: 200.
  • Autorun: LOCK
    Periodic function automatically starts after init and can't be stopped.

Files

Header Files

The following headers are automatically included in modules.h

• aoa_t4.h

Source Files

• modules/sensors/aoa_t4.c

Raw aoa_t4.xml file:

<!DOCTYPE module SYSTEM "module.dtd">
 
<module name="aoa_t4" dir="sensors">
  <doc>
    <description>
      Angle of Attack (AOA) sensor using angle input from a modiefied hall servo connected to a T4 Actuators Board.
      For the hardware and software used to make your own T4 Actuators board, find all information here:
 
        https://github.com/tudelft/t4_actuators_board/
 
      To make it work, the motor of the servo needs to be removed, only the hall sensors is used for angle feedback.
      If the MOTOR is NOT REMOVED from the servo there will be to much friction and the sensor will NOT WORK properly.
 
      Budget wise it is a flexible solution for angle of attack sensor if one uses a T4 Actuators Board already.
 
      Aditionall a second servo can added to be assigned to fuction as a SideSlip angle (SSA) sensor.
 
      If SSA is added, it is assumed that both sensors are the same, offset and direction can be set to different values.
 
      A Servo modified for sensor use which works well is a Feetech STS3032. It is a 360 degree serial bus servo with hall sensor feedback.
 
      Simply add the "aoa_t4" module to your myname_airframe.xml file to be able to use this solution.
      Also for initial offset determination, enabeling the SYNC message is very helpfull. Just add the SYNC_SEND_AOA_T4 define.
 
      For a 3D design of a vane that can be 3D printed and mounted on the  servo used, download it here:
 
    </description>
    <define name="AOA_T4_SERVO_ID" value="10" description="Set the Servo ID of servo to use as an Angle Of Attack(AOA) sensor."/>
    <define name="AOA_T4_ANGLE_OFFSET" value="3.14"  description="How the sensor is physically  mounted, a global offset in radian corresponding to the sensor mounting (default: 3.14)"/>
    <define name="AOA_T4_OFFSET" value="-0.123" description="Initial offset on the neutral angle value."/>
    <define name="AOA_T4_REVERSE" value="TRUE|FALSE" description="Set to TRUE to reverse AOA output rotation direction (sign)"/>
    <define name="AOA_T4_USE_FILTER" value="TRUE|FALSE"  description="Filter the AOA angle sensor output to avoid to much angle fluctuation"/>
    <define name="AOA_T4_FILTER" value="0.08" description="If filtered is true, then set how much to filter the output"/>
    <define name="AOA_T4_SYNC_SEND" value="TRUE|FALSE" description="Enable telemetry report from AOA or SSA sensor, best set to TRUE to determine the neutral angle to set in offset"/>
    <define name="AOA_T4_USE_COMPENSATION" value="TRUE|FALSE" description="Compensate the output"/>
    <define name="USE_AOA" value="TRUE|FALSE" description="Enable AOA sensor values to the state (default: TRUE)"/>
    <define name="AOA_T4_COMP_A1" value="0.0" description=""/>
    <define name="AOA_T4_COMP_B1" value="0.0" description=""/>
    <define name="AOA_T4_COMP_A2" value="-0.34" description=""/>
    <define name="AOA_T4_COMP_B2" value="0.0" description=""/>
    <!-- Optionally if a SideSlip Angle(SSA) sensor is available -->
    <define name="SSA_T4_SERVO_ID" value="9" description="Set the Servo ID of servo to use as an SideSlip Angle(SSA) sensor"/>
    <define name="SSA_T4_ANGLE_OFFSET" value="3.14"  description="How the sensor is physically  mounted, a global offset in radian corresponding to the sensor mounting (default: 3.14)"/>
    <define name="SSA_T4_OFFSET" value="-0.456" description="Initial offset on the neutral angle value."/>
    <define name="SSA_T4_REVERSE" value="TRUE|FALSE" description="Set to TRUE to reverse AOA output rotation direction (sign)"/>
    <define name="SSA_T4_USE_FILTER" value="TRUE|FALSE"  description="Filter the AOA angle sensor output to avoid to much angle fluctuation"/>
    <define name="SSA_T4_FILTER" value="0.15" description="If filtered is true, then set how much to filter the output"/>
    <define name="USE_SIDESLIP" value="TRUE|FALSE" description="Enable SSA sensor values into the state"/>
  </doc>
  <settings>
    <dl_settings>
      <dl_settings name="AOA T4">
        <dl_setting var="aoa_send_type" min="0" max="1" step="1" shortname="Send AOA or SSA" module="modules/sensors/aoa_t4" values="AOA|SIDESLIP"/>
        <dl_setting var="aoa_t4.offset" min="-3.14" max="3.14" step="0.01" shortname="AOA Offset" module="modules/sensors/aoa_t4" param="AOA_OFFSET" unit="rad" alt_unit="deg"/>
        <dl_setting var="aoa_t4.filter" min="0.0" max="0.95" step="0.01" shortname="AOA Filter" module="modules/sensors/aoa_t4" param="AOA_FILTER"/>
        <dl_setting var="ssa_t4.offset" min="-3.14" max="3.14" step="0.01" shortname="SSA Offset" module="modules/sensors/aoa_t4" param="SSA_OFFSET" unit="rad" alt_unit="deg"/>
        <dl_setting var="ssa_t4.filter" min="0.0" max="0.95" step="0.01" shortname="SSA Filter" module="modules/sensors/aoa_t4" param="SSA_FILTER"/>
        <dl_setting var="aoa_t4_a1" min="-1" max="1" step="0.001" shortname="Comp A1" />
        <dl_setting var="aoa_t4_b1" min="-1" max="1" step="0.001" shortname="Comp B1" />
        <dl_setting var="aoa_t4_a2" min="-1" max="1" step="0.001" shortname="Comp A2" />
        <dl_setting var="aoa_t4_b2" min="-1" max="1" step="0.001" shortname="Comp B2" />
      </dl_settings>
    </dl_settings>
  </settings>
 
  <header>
    <file name="aoa_t4.h"/>
  </header>
  <init fun="aoa_t4_init()"/>
  <periodic fun="aoa_t4_update()" freq="200."/>
  <makefile target="ap|sim|nps">
    <file name="aoa_t4.c"/>
  </makefile>
 
</module>